In a wireless local area network (Wireless Local Area Networks, WLAN), a basic service set (Basic Service Set, BSS) is a basic component part of the wireless local area network. When a user terminal needs to access a basic service set network, the user terminal needs to discover, through scanning, the basic service set network and an access point (Access Point, AP) of the basic service set network. Scanning methods are classified into two modes: active scanning and passive scanning, where when the user terminal is in an active scanning mode, the user terminal sends a probe request message to the access point through unicast or broadcast on a channel, and then waits for corresponding probe response message sent by the access point within a certain period of time. In this manner, the user terminal actively discovers a basic service set network and acquires an associated attribute of the basic service set network. The probe request message sent by the user terminal includes a service set identifier (Service Set Identifier, SSID) and a basic service set identifier (Basic Service Set Identifier, BSSID). After receiving the probe request message, the access point feeds back a corresponding probe response message to the user terminal if the following conditions are satisfied: The SSID is a wildcard SSID or matches an SSID of an extended service set (Extended Service Set, ESS), and the BSSID is a wildcard BSSID or a BSSID of the access point.
However, in the prior art, when the access point feeds back the probe response message to the user terminal, the access point does not send the probe response message to the user terminal immediately, but arranges the probe response message in a transmission queue, and then acquires a message sending opportunity in a distributed competition manner. However, time during which the user terminal waits for a response is fixed. After the user terminal ends scanning of this channel, the access point may still continuously send the probe response message to the user terminal because the access point does not know that the user has left, which leads to a waste of channel resources.